Phenolic couplers

ABSTRACT

Phenolic color couplers which have alkyl groups bonded to at least one aromatic ring thereof, the number of carbon atoms in said alkyl groups totaling at least 12, and the phenolic nucleus of said coupler bearing an alkyl substituent in the meta position having at least two carbon atoms. The couplers exhibit unusual stability to light, heat, and moisture, and are preferably incorporated in silver halide emulsions by the solvent dispersion technique.

United States Patent [191 Ramello Nov. 13, 1973 1 PHENOLIC COUPLERS [75] Inventor: Piero Ramello, Turin, Italy [73] Assignee: Minnesota Mining and Manufacturing Company, Saint Paul, Minn.

[22] Filed: Oct. 14, 1971 [21] Appl. No.: 189,136

Related U.S. Application Data [63] Continuation-impart of Ser. No. 45,205, June 10,

I970, abandoned.

[52] U.S. Cl. 96/100 [51] Int. Cl G03c 1/40 [58] Field of Search 96/100, 55

[56] References Cited UNITED STATES PATENTS 2,908,573 10/1959 Bush et a1. 96/100 2,920,961 l/1960 Bush et a1. 96/100 3,620,745 11/1971 Seymour 96/100 3,652,286 3/1972 Credner et a1... 96/100 3,658,537 4/1972 Credner et a1 96/100 3,700,454 10/1972 Sakamoto et a1. 96/100 Primary Examiner-Norman G. Torchin Assistant Examiner-Richard L. Schilling Attorney-Alexander, Sell, Steldt & Delahunt [5 7] ABSTRACT 12 Claims, No Drawings PHENOLIC COUPLERS This application is a continuation-in-part of application Ser. No. 45,205, filed June 10, 1970, now abandoned.

The present invention relates to color couplers useful in color photography, and to photographic silver halide emulsions containing such couplers. More specifically, the invention relates to phenolic couplers particularly suitable for incorporation in hydrophilic colloidal binder (e.g., gelatin) emulsions by the solvent dispersion technique, such couplers giving rise to cyan dyes by color development.

It is known to the art that couplers of the phenolic type are capable of reacting with the oxidation product of N,N-dialkyl-paraphenylene diamine type developers to form cyan images in silver halide photographic elements. It is greatly desired that such dye images be highly stable to light, heat, and moisture. It is further desired that such dyes have the capacity to be incorporated by the solvent dispersion technique in silver halide photographic emulsions.

Phenolic couplers of the type described in US. Pat. Nos. 2,367,531; 2,369,929 and 2,423,730 generally either exhibit poor stability to light, heat, or moisture, or are not capable of being incorporated in a silver halide photographic emulsion by the solvent dispersion technique. Such deficiencies generally reduce desirability of employing such couplers in silver halide emulsions.

It is an object of the present invention to provide phenolic couplers which are capable of reacting with the oxidation product of a primary aromatic amine developer to form a dye which is highly stable to light, heat, and moisture.

A second object of the invention is to provide silver halide photographic emulsions which have such couplers incorporated therein by the solvent dispersion technique.

Briefly, the present invention relates to a phenolic photographic color coupler which includes a phenolic nucleus substituted in the 4-position thereof with substituent X, a group (e.g. l-l, chloro) which is expelled during reaction of said coupler with the oxidation product of a p-phenylenediamine developer to form a dye. The phenolic nucleus has substituents R, R, and R respectively in the 3, 5 and 2-positions thereof wherein R and R, each independently represent a hydrogen atom or an alkyl group having at least two carbon atoms (at least one of R and R, being different from hydrogen) and wherein R is a -Nl-1COY group in which Y is aryl, cycloalkyl, aryloxyalkylidene, alkaryloxyalkylidene, aralykylidene or arylamino. The alkyl groups covalently bonded to aromatic rings of the coupler must contain a total of at least 12 carbon atoms.

The couplers of the invention preferably are of the formula Z NHCOY wherein R, R,, X and Y are as described a'bdvej'i is hydrogen or halogen (e.g., chloro, bromo), and wherein the total number of carbon atoms in alkyl groups covalently bonded to aromatic rings of the coupler is at least 12.

The invention further relates to silver halide photographic emulsions including a hydrophilic colloidal binder which has dispersed therein a coupler of the above-described formula.

The couplers of the present invention have been found to provide dyes which have surprisingly great stability to light and to moist heat. It has been found generally that the stability of such dyes is at least partially dependent upon the technique utilized in incorporating the couplers of the invention in silver halide emulsions. By far the best results have been obtained utilizing the well-known solvent dispersion techniques described, for example, in US. Pat. Nos. 2,322,027; 2,801,170; 2,801,171; 2,870,012 and 2,991,177. The couplers of the present invention are substantially insoluble in water but are soluble in the generally high-boiling organic solvent utilized in the solvent dispersion technique.

Briefly, the solvent dispersion technique involves first dissolving a coupler in a substantially water-immiscible organic solvent, and then dispersing the so-prepared solution as extremely fine droplets in the hydrophilic colloidal binder material of a silver halide photographic emulsion. Gelatin is the preferred hydrophilic colloidal binder, but other polymeric colloidal binder materials known to the art can also be utilized. Photographic emulsions of the invention may include the usual photographic adjuvants, such as wetting agents, sensitizers, stabilizers, and the like.

In the comparisons reported below, samples of emulsions spread on transparent supports containing, respectively the couplers according to the present invention and those known from the literature, were exposed to red light through a scale of decreasing densities and subjected to the developing process in a color developing bath comprising a paraphenylene diamine. After the colored image was obtained, the samples were respectively subjected to light fastness tests, by exposing them to the radiations in a fadometer with a Xenon lamp, and to tests of resistance to moist heat at a temperature of 194.0F (90C) and at percent RH. Thereafter, the optical density percent drop measured at the peak of the relative absorption curve was read. The colored images derived from the couplers according to the present invention have proven to be stable to light as those derived from the couplers known from the literature but they have proven to be decidedly more stable to moist heat than the images obtained from the couplers known from the literature.

The stability of the dyes of the present invention appears to depend primarily on the presence of at least one alkyl group having at least two carbon atoms which is covalently bonded to the phenolic nucleus of the coupler in the meta position. Stability appears to be substantially independent of other substituents bonded to the phenolic nucleus. However, those alkyl substituents which may be covalently bonded to an aromatic ring of the Y group may, together with alkyl groups represented by R or R, be required to lend ballasting properties to the couplers of the invention. It is required that. the couplers of the present invention contain at least one alkyl group bonded to an aromatic ring thereof such that alkyl groups covalently bonded to aromatic rings of the coupler contain a total of at least 12 carbon atoms. it is desired that such carbon atoms total not more than 20 in number in order to provide efficient utilization of the couplers of the invention in photographic emulsions. It is preferable that the at least m 03 one alkyl group represented by R and/r R contain l NHCO from two to 15 carbon atoms. Cl

The invention may be more clearly understood by reference to the following illustrative examples: 5 CHEM Exemplary of couplers of the invention are the following: 1

- iallri C3115 $1 1a. Preparation of 4-chloro-5-ethyl-phenol: one mol of methyl-phenol was dissolved in anhydrous ether or other suitable solvent and chlorinated with one mol of S0,,Cl at 77.0F (25C). After evaporation l Coupler l 2-(2', 4'-di-tert-amyl-6'-chloro-phenoxy acetamido)-4,6-dichloro-S-ethyl-phenol.

E of the ether, the product was purified by distillation {b.p,: 456 F (236C) 750 mm) lb. Preparation of 2-ammo-4-chloro-5-ethyl-phenol. CHEM 216 g of 4-chloro-5-ethyl-phenol were dissolved in 1,500 ml of CHCl and were treated with 60 m] of l HNO ,d= 1.52 at 3239.2F (04C).Then the 4. 0H solution was washed with water and the chloroform 22115 was evaporated off. The residue, after usual purifi- NH0 0 cations was reduced in ammonia-water solution with Na S O,. The white solid was crystallized from benzene (mp. 282.2F (139C). 1 10. Preparation of 2(2', 4'-di-tert-amyl-phenoxy ac- 35 etamido) -4-chloro-5-ethyl-phenol. One mol of 2-amino-4-Cl-5-ethylpheno1 was dissolved in 30 parts of acetone-water (90 10 by volume) and cold-treated with one mol of 2,4-di-tert-amylphenoxy acetyl chloride under stirring. The whole Was refluxed for 1 hour. The acetone was then partially evaporated off, the mass was diluted, with ice 5. OH water and filtered at 32.0F (0C). The crude material after purification, melted at about 456F (236C). 1d. Preparation of the coupler. 38 g of 2(2',4'-ditert-amylphenoxy-acetamido)-4-chloro-5- C nHai ane and treated at 104.0F (40C) with 24 g of S0 NHCO- H C1,. After 1 hour the whole was poured in ice water CF obtaining a paste which was converted into powder by treatment with petroleum ether. The material CHEM was crystallized from ligroin, obtaining the product melting at about 273.2C (134C). (E1 Coupler l 2(2',4-di t-amyl-phenoxyacetamido)-4- 8 OH chloro-S-propylphenol.

| 2a. Preparation of m-nitro-propiophenone: 1,000 g C) --NHCOCH2 of propiophenone was added drop-wise to 3,000 g of HNO at 9C i 1. Then the solution was Collar poured in 15.000 ml ice-water mixture. The crude product became solid after washing again with 30.000 ml of ice-water. The solid product was filtered, washed with water and crystallized from 5 l.

of methanol. 41') g of pure m-nitro propiophenone 4 (mp. 97-98C) were obtained.

HM 2b. Preparation of mpropyl-aniline. 399 g of mnitropropiophenone, 1,350 ml of triethylene-glycol and 710 ml of N H -H O were refluxed for 1 ethylphenol were suspended in 300 ml of dry diox-' hour. Temperature was allowed to decrease to 105C and catalitic amounts of 50% KOH were added very cautiously. After one hour 900 g of 50% KOH were added. The solution was distilled under vacuum till the temperature reached 190C. The collected mixture was extractead with benzene. After benzene evaporation the product was recovered by distillation under vacuum. Grams 206 of pure m-propyl-aniline were obtained.

2c. Preparation of m-propyl-phenol: A mixture of 346 ml of cone. HCl, 800 ml of water and 186.7 g of m-propyl aniline was cooled to -3C 1 1 and diazotized (during one hour) with 99 g of NaNO in 330 ml 11 0. The diazonium salt solution was poured (with stirring) in 5 l of percent l-1 SO preheated and kept at 60C. The m-propyl-phenol,

so obtained, was extracted with Cl-lCl and purified' taining 86.7 g (b.p. 129137/12mm) of a product of sufficient purety for the following synthesis. 2e. Preparation of 2-nitro-4-chloro-5-propyl-phenol: 85 g of 4-chloro-5-propyl-phenol in 800 ml of CHCl was nitrated at 0C with 31.4 g of HNO in 220 ml CHCl Then the chloroform solution was washed with water until the washings were neutral. The Cl-lCl was evaporated obtaining 102.3 g of the crude nitrophenol which was sufficiently pure for the following steps.

2f. Preparation of 2-amino-4-chloro-5-propylphenol: 101 g of the preceding nitrophenol was dissolved in 200 ml of methanol and poored into 3 l' of 10% NaOH. The nitro phenolate solution was reduced with 220 g of Na S Q, at 6080C. The solution was cooled to 0C and neutralized with CH COOH. The product was filtered and washedwith water. 79 g of product was obtained (m.p. 81-90C). After purification via the hydrochloride salt, the free base was recrystallized from heptone obtaining 22.5 g of pure product (m.p. l01-103C). (N 7.62% C 58.24% H 6,54%)

2g. Preparation of 2(2,4'di t-amyl phenoxy acetamido) 4-chloro-5-propyl-phenol: To 20.2 g of 2 amino-4-chloro-5-propyl-phenol (dissolved in 150 ml of acetone) was added 33.8 g of 2.4 di t-amyl phenoxy-acetyl-chloride. Then 16,2 g of N,N-diethylaniline were added. After 1 hour of reflux the solution was poored into an ice-water mixture (1,000 ml) containing 50 ml of cone. HCl. The obtained product was then filtered and recrystallized from 230 m1 of CH CN 28 3 g of the coupler were obtained (m.p. 200-202C).

Coupler 2 2-benzoyl-amido-4-chloro-5-pentadecylphenol.

3a. Preparation of the 4-chloro-5-pentadecyl-phenol.

intermediate: 1 mol of metapentadecylphenol was dissolved in 1,000 ml. of anhydrous diethyl ether. To the solution. thus obtained one mol of SO Cl was added dropwise. The ether was evaporated off and the residue was distilled (b.p. 404.6F (207C) (about 1 mm Hg) heating with running water at 59.0F (15). The:

material was crystallized three times from acetonitrile discarding the oily residue and filtering each time after standing long at 32.0F (0C). The product melts at about 105.8F (41C).

3c. Preparation of the 2-amino-4-chloro-5- pentadecyl-phenol intermediate: 580 g of nitro-4- chloro-S-pentadecyl-phenol were dissolved in 2,000 ml of ethanol at 158.0F (C). The alcohol solution was poured under stirring in 6,000 ml of water pre-heated at 158.0 176.0F (70 C) to which 500 ml of concentrated Nl-l had been just added. Then, 1,100 g of Na S O were added rather quickly until decoloration was achieved. The mass was diluted with 5 kg of ice while stirring thoroughly. The material was filtered and washed with water, then crystallized from ligroin or acetonitrile by pre-heating the required amount of the solvent and cooling quickly the solution so that the product remained a short time in solution, in the hot. The product depending on the degree of purity melted at temperatures slightly different around 176.0F (80C) 2d. Preparation of the coupler: 1 mol of 2-amino-4- chloro-S-pentadecyl-phenol in 10 parts of anhydrous Cl-l CN were treated with 1 mol of benzoyl chloride and refluxed for at least two hours. After subsidence of the development of hydrogen chloride gas and after cooling, the material was filtered, washing with acetonitrile and then recrystallized from acetonitrile (m.p. 302.0F (150C)) Coupler 3 2-phenoxyacetamido-4-chloro-S- pentadecyl-phenol:

the product was prepared in a way similar to coupler 2, by using phenoxy-acetyl chloride in place of the benzoyl chloride. The purification was carried out by washing with methanol and crystallizing then from little acetic acid (m.p. 298.4F (148C)).

Coupler 4 2-a-phenoxy-butiroylamido-4-chloro-5- pentadecyl-phenol.

The product was prepared like the coupler 2, by using a-phenoxy-butiroyl chloride in place of the benzoyl chloride. The product was purified by crystallization from acetonitrile (m.p.: about 181.4"F 053 Coupler 5 2-phenylureido-4-chloro-5 -pentadecylphenol:

17 g of 2-amino-4-chloro-5-pentadecyl-phenol were hot dissolved in ml of dioxane. The solution was quickly cooled under stirring, obtaining a fine suspension. To the stirred suspension 6 g of phenyl isocyanate in 50 ml of dioxane were added. The

whole was then heated at 194.0F (90C) for two hours, cooled and filtered. The product was crystallized from methanol (m.p. 302.0 (C)) Coupler 6 2-hexahydro-benzoyl-amido-4-chloro-5- pentadecyl-phenol:

This coupler was prepared like the coupler 2, by using hexahydrobenzoyl chloride in place of the benzoyl chloride. The coupler was purified by crystallization from acetonitrile (m.p.: 181.4"F

(83C)). Coupler 7 2-hexahydrobenzoylarnido-4,6-dichloro-5- pentadecyl-phenol: 41 g of the coupler No. 6 were dissolved in 200 ml of anhydrous dioxane and treated with 7.3 ml of SO Cl The whole was left undisturbed for 12 hours at room temperature, and then the solution was poured in ice water. An oily product was obtained which after a long standing became solid and filtrable. The crude material was purified by crystallization from petroleum ether (m.p.: about 140.0F (60C)). Coupler 8 2-phenyl-acetamido-4,6-dichloro'5- pentadecyl-phenol:

93. Preparation of the intermediate coupler 2- phenyl-acetarnido-4-chloro-5-pentadecyl-phenol: this intermediate was prepared in a way similar to coupler 2 by using phenylacetyl chloride in place of the benzoyl chloride. The product was purified by crystallization from acetonitrile (m.p.: about 163.4F (73C)).

9b. Preparation of the coupler: 19.2 g of 2-phenylacetamido-4-chloro-S-pentadecyl-phenol were dissolved in 100 ml of anhydrous dioxane and treated with at least 3.35 ml of SO CI After standing for 20 hours at room temperature, the material was poured in 700 g ofa water-ice mixture. The precipitate was filtered and washed with water.

Coupler 9 2-benzoyl-amido-3-pentadecyl-4,o-dichlorophenol:

10a. m-pentadecyl-phenol: a sample of the 3M commercial product Cardolite NC 510 purified by distillation was used.

10b. 2,4-dichloro--pentadecyl phenol: 1 mol of mpentadecyl-phenol was dissolved in 1000 ml of anhydrous ether and 2.1 mols of SO CI were added dropwise therein in the course of few hours at '77.0F (25C). After evaporation of the ether, the product was distilled (b.p.: about 422.6F (217C) /1 mm Hg) c. Preparation of the 2-nitro-3-pentadecyl-4,6- dichloro-phenol intermediate: 827 g of 2,4- dichloro-5-penta-decyl-phenol were dissolved in 4,000 ml of chloroform. The solution was nitrated at 37.4F (3C) with 98 ml of HNO d 1.52. After some hours the solution was washed with cold water, then the chloroform was evaporated off. The residue was crystallized from acetonitril.

10d. Preparation of the 2-amino-3-pentadecyl-4,6- dichloro-phenol intermediate: 920 g of 2-nitro-3- pentadecyl-4,6-dichloro-phenol were dissolved in 3,000 ml of hot ethanol and poured under stirring in 6,000 ml of water preheated at 167.0F (75C) and containing 600 ml of concentrated NH To the orange-colored suspension 1,800 g of Na S CL, were added portionwise in the course of few minutes. After the decoloration was achieved, the mass was neutralized with acetic acid and diluted in ice. The material was filtered and washed with water. The crude product was crystallized from acetonitrile (m.p.: about l49.0F (65C)).

l0e. Preparation of the coupler: 18 g of 2-amino-3- pentadecyl-4,-dichloro-phenol were condensed with benzoyl chloride by the same procedure used in the case of the coupler 2. The crude material was crystallized from ligroin (m.p.: about l95.8F (9 1C) Coupler l0 2-hexahydrobenzoyl-3-pentadecyl-4,6- dichloro-phenol. The product was prepared in a way similar to coupler 9 but using hexahydrobenzoyl chloride in place of the benzoyl chloride. The coupler was again crystallized from ligroin (m.p.: about 145.4F (63C)).

Coupler ll Z-phenyl-acetamido-3-pentadecyl-4,6- dichloro-phenol: the coupler was prepared in a way similar to coupler 9 but using phenylacetyl chloride in place of the benzoyl chloride. The product was crystallized from ligroin (m.p.: about l77.8F (8lC)).

The behaviour of the couplers of the present invention was tested in comparison with the following couplers known from the literature:

12. OH CrHn cafimmocmo-Q-onm CH3 13. OH CaHu CI \NHC ocmo -CH cut-Y 2:1

NHC ocalo-cnin xvncocmo-Q-mm CH3 I 31 o1 NHC ocmoQ-mm CH3 1 c1 NHC ocmoQ-cnm Surprisingly it has been found that the couplers according to the present invention are much more stable to moist heat. For example, the couplers l to 17 of which the first 12 according to the present invention and those 12 to 17 outside the present invention and known from the literature, were tested in the following way: 2g of coupler were dissolved in 6 ml of dibutyl hthalate and l2 ml of ethyl acetate and the solution thus obtained was emulsified with 40 ml of a 4 percent gelatin solution. The emulsion was then diluted with water to ml and a fraction thereof containing 0.002 mol of coupler was mixed with 200 ml of a silver brorno chloride emulsion at 7 percent of gelatin, and the resulting emulsion was spread on a polyester support. The different samples of emulsion, each corresponding to a different coupler, were exposed to red light through a scale of decreasing densities and then developed with a developing bath having the following formulation: sodium hexametaphosphate 2g anhydrous sodium sulfite I 2-amino-5-diethylamino toluene hydrochloride 3g sodium carbonate, monohydrate potassium bromide 2g water to make 1000ml Some of the specimens obtained were exposed for 10 hours in a fadometer to a Xenon lamp, others were stored for 24 hours at a temperature of 194.0F (90C) and at 75 percent R.l-l. All the specimens proved to be stable to light to the same extent, but under moist heat the losses (A) of optical density (D) shown in the table occurred, wherein:

AD% (initial D- final D/initial D) 100 TABLE COUPLER A D .What I claim is:

l. A silver halide photographic emulsion including a hydrophilic colloidal binder having dispersed therein a phenolic photographic coupler having a phenolic nucleus substituted in the 4-position thereof with a group the oxidation product of a p-phenylenediamine developer, said phenolic coupler having substituted in the 3-, 5-, and 2-positions respectively groups R, R and R wherein R and R each independently represent a hydrogen atom or an alkyl group having at least two carbon atoms, at least one of R and R being different from hydrogen, and wherein R is a -NHCOY group in which Y is aryl, cycloalkyl, arloxyalkylidene, alkaryloxyalkylidene, aralkylidene or arylamino, and wherein the total of carbon atoms in alkyl groups covalently bonded to aromatic rings is at least 12 carbon atoms.

2. The emulsion of claim 1 wherein said coupler is 2- (2,4'-di-tert-amyl-6'-chloro-phenoxy-acetamido)-4,6- di-chloro-S-ethylphenol.

3. The emulsion of claim 1 wherein said coupler is 2(2',4'-di t-amyl-fenoxyacetamido )-4-chloro-5-propylphenol.

4. The emulsion of claim 1 wherein said coupler is 2- benzoylamideo-4-chloro-5-pentadecylphenol.

5. The emulsion of claim 1 wherein said coupler is 2- (phenoxyacetamido)-4-chloro-5-pentadecylphenol.

6. The emulsion of claim 1 wherein said coupler is 2' a-phenoxy-butyroylamido-4-chloro-5- pentadecylphenol.

7. The emulsion of claim 1 wherein said coupler is 2- phenylureido-4-chloro-5-pentadecylphenol.

8. The emulsion of claim 1 wherein said coupler is 2- hexahydrobenzoylamido-4-chloro-5- pentadecylphenol.

9. The emulsion of claim 1 wherein said coupler is 2- hexahydrobenzoylamido-4,6-dichloro-5- pentadecylphenol.

10. The emulsion of claim 1 wherein said coupler is 2-phenylacetylamido-4,6-dichloro-5- pentadecylphenol.

11. The emulsion of claim 1 wherein said coupler is 2-hexahydrobenzoyl-3-tentadecyl-4,6-dichlorophenol.

12. The emulsion of claim 1 wherein said coupler is Z-phenyI-acetamido-3-pentadecyl-4,6 -dichlorophenol. 

2. The emulsion of claim 1 wherein said coupler is 2-(2'',4''-di-tert-amyl-6''-chloro-phenoxy-acetamido)-4,6-di-chloro-5 -ethylphenol.
 3. The emulsion of claim 1 wherein said coupler is 2(2'',4''-di t-amyl-fenoxyacetamido)-4-chloro-5-propyl-phenol.
 4. The emulsion of claim 1 wherein said coupler is 2-benzoylamideo-4-chloro-5-pentadecylphenol.
 5. The emulsion of claim 1 wherein said coupler is 2-(phenoxyacetamido)-4-chloro-5-pentadecylphenol.
 6. The emulsion of claim 1 wherein said coupler is 2- Alpha -phenoxy-butyroylamido-4-chloro-5-pentadecylphenol.
 7. The emulsion of claim 1 wherein said coupler is 2-phenylureido-4-chloro-5-pentadecylphenol.
 8. The emulsion of claim 1 wherein said coupler is 2-hexahydrobenzoylamido-4-chloro-5-pentadecylphenol.
 9. The emulsion of claim 1 wherein said coupler is 2-hexahydrobenzoylamido-4,6-dichloro-5-pentadecylphenol.
 10. The emulsion of claim 1 wherein said coupler is 2-phenylacetylamido-4,6-dichloro-5-pentadecylphenol.
 11. The emulsion of claim 1 wherein said coupler is 2-hexahydrobenzoyl-3-tentadecyl-4,6-dichlorophenol.
 12. The emulsion of claim 1 wherein said coupler is 2-phenyl-acetamido-3-pentadecyl-4,6-dichlorophenol. 